Childhood overweight and obesity rates - In Spain, around 41% of children aged 6 to 9 years were overweight and/or had obesity in 2015

Although the overall prevalence of overweight and obesity in children and adolescents has fallen slightly over the past decade, the rates of both conditions have increased in the most disadvantaged neighbourhoods, according to a study that included more than one million children in Catalonia, Spain, which was carried out by the Barcelona Institute for Global Health (ISGlobal) - a centre supported by ‘la Caix’ - and the IDIAPJGol Institute.

Levels of childhood overweight and obesity have plateaued in many middle- and high-income countries over the past decade, but prevalence rates remain high. In Spain, around 41% of children aged 6 to 9 years were overweight and/or had obesity in 2015 - the second-highest prevalence rate in Europe. In the Catalonia region, childhood overweight and obesity rates are similar to those of Spain as a whole.

The study, ‘Time Trends and Sociodemographic Factors Associated With Overweight and Obesity in Children and Adolescents in Spain’, published in Jama Network Open, was based on data from 1.1 million children and adolescents in Catalonia aged 2 to 17 years with at least one height and weight record in the Information System for Research in Primary Care (SIDIAP) between 2006 and 2016. The children were divided into three age groups: 2-5 years, 6-11 years and 12-17 years. Prevalence rates and time trends for overweight and obesity were calculated and stratified by socio-demographic characteristics: age, sex, urban/rural residence, nationality, and the socioeconomic deprivation score of the family's census tract, as calculated using the MEDEA index.

In general, the findings showed that the prevalence of overweight and obesity decreased slightly in both sexes and all age groups. During the ten-year study period, rates of overweight and obesity fell from 40% to 38% in girls aged 6 to 11 years and from 42% to 40% in boys of the same age group. However, prevalence rates rose in the most deprived urban areas and in children of non-Spanish nationalities.

In areas with lower socio-economic levels, rates of overweight and/or obesity increased slightly, whereas wealthier areas saw a significant decrease, leading to a wider inequality gap. For example, between 2006 and 2016, the obesity rate in girls aged 6 to 11 years fell by 15.8% in neighbourhoods with the highest socio-economic level but increased by 7.3% in the most disadvantaged areas.

"The data can be extrapolated to Spain as a whole and they may reflect the impact of the 2008 economic crisis, which exacerbated inequality within urban areas and increased the number of vulnerable families, who may be more likely to follow unhealthy nutritional habits," said Jeroen de Bont, a researcher at ISGlobal and IDIAPJGol and lead author of the study.

Children from North, Central and South America - the vast majority of whom were Latin American - had the highest rates of overweight and/or obesity. Specifically, 56% of boys and 50% of girls of these nationalities between the ages of 6 and 11 years were overweight and/or obese.

"With the exception of Latin America, children of non-Spanish nationalities were less overweight and/or obese at the start of the study, but their prevalence rates increased over the years until they reached the levels of overweight and/or obesity in Spanish children. This trend was especially pronounced in African and Asian children," added de Bont. The children's "gradual adoption of the Western lifestyle and eating habits" could explain these findings, he added.

Children of African and Asian nationalities saw the largest increase in overweight or obesity during the study period.

"These prevalence rates are alarming, since obesity in childhood and adolescence is associated with health consequences later in life, including cardiovascular, musculoskeletal and endocrine diseases," warned Talita Duarte-Salles, a researcher at IDIAPJGol and co-coordinator of the study.

The study also found that children between 6 and 7 years of age were the most vulnerable to developing overweight and/or obesity.

"These findings demonstrate the importance of public health promotion programmes at early ages where primary healthcare professionals can play a key role in identifying overweight children during routine visits," added Duarte-Salles.

"Specific health initiatives focused on the most vulnerable groups are urgently needed to address the high prevalence of childhood overweight and obesity in Spain and worldwide," concluded ISGlobal researcher Martine Vrijheid, co-coordinator of the study.